Combined fuse and indicator



p 15, 1953 H. H. MOHRING 2,652,466

COMBINED FUSE AND INDICATOR Filed Feb. 29, 1952 m INVENTOR HERMAN H.Momzme Patented Sept. 15, 1953 U NIT ED STATE S PATENT OFFICE 2,652,466,COMBINED; FUSE AND INDICATOR Herman Hi Mohring, Omaha, Ncbr.

Application February 29, 1952, SerialNo. 274,133"

2 Claims. 1

This invention relates toan improved fuse plug assembly of the typewhich incorporates a lamp for indicating the condition of the fuse.

It is among the objects of the invention to provide an improved fuseplug assembly including a plug body, a replaceable fuse mounted in thebody, and a glow lamp mounted in the body to be energized only when thefuse is absent or defective; which will fit into a socket provided for aconventional plug type fuse; which provides a replaceable fuse of lessexpensive construction than the usual plug type fuse and one which iseasier'to replace; which is entirely safe and fireproof and which issimple and durable in construction, economical to manufacture,andpositive and effective in operation.

Other objects and advantages will become apparent from a considerationof the following description and the appended claims in conjunction Cwith the accompanying drawing wherein:

Figure 1' is a top plan view of a fuse plug assembly illustrative of theinvention;

Figure 2 is across sectional view on the line 2-2 of Figure 1;

Figure 3 is a cross sectional View on the line 3-3 of Figure 2;

Figure 4 is a cross sectional view on the, line 4-4 of Figure 2; and

Figure 5 is a cross sectional view similar to Figure 2, but showing theparts in a different relative position from that illustrated in Figure2.

With continued reference, to the drawing, the fuse assembly comprises aplug body It of electrically insulative material and of cylindricalshape having a bore or recess ll therein opening, through one end ofthebody, the other end of the body being closed by an end wall I2" ofpartly conical shape. An outwardly projecting annular lateral flange I3is provided around the open end of the body and the outercylindrical'surface of the body between the flange l3, and the end wallI2 is provided with a screw thread formation M of substantiallysemicircular cross sectional shape. Athin walled shell I5 of cylindricalshape and of suitable electrically conductive sheet material, such assheet brass, closely surrounds the body Ill between the flange [3' andthe end wall It and is provided'with a screw thread formationlfireceiving the screw thread formation M on the shell and adapted tothread into a fuse plug receptacle of known construction.

A center contact lI-of electrically conductive material-extends throughtheend wall 2 of the body centrally ofthe end wall and has a flat headportion on its outer end overlying the ad'- jacen-tend portion: or! theend wall I2 of the:

body.

A first strip 18- of electrically conductive resilient material isconnected at one end to the shell l5 at the end of the latter adjacenttheconductive resilient material issecured at one end to the centercontact H at the end of the latter within the body and extends along theside of the recess IT opposite the strip It and longitudinally of thebody and ina direction fromthe end wall 12 towardthe flange 13 of thebody.

As is particularly illustrated in Figure 3, the portion-of the recess llreceiving thestrips l8 and I9 is of elongated, rectangular crosssectionalshape and thestrips lfl-and- |9- are disposedalongthe opposednarrowersides of this portion of the recess. The recess includes alateral extension of semicircular cross sectional shape extending fromone of the wider sides of the portion ofrectangular crosssectional'shape for a purpose; to be presently disclosed.

'A- cover 20- of suitable material, such as thin sheet metal, isdisposed on the open endof the body [0' and has acylindrical flangeportion 2! closely surrounding the flange I3 of the body and an endwall'portion' 22' which overlies the open end of the body H)" incovering relationship to the open end'of the semi-circularextension ofthe recess Il' inthe body. This cover has an aperture 23 of elongated;rectangular shape registering with the rectangular shaped portion oi therecess II and a small hole 24 opening into the semi-circular extensionof the recess II.

A glow lamp 25 is mounted in the extension of the recess I l and extendsat its end remote from its base through the aperture 24 in the cover 20;so that the lamp is clearly visible from the exterior of the flanged endof the housing.

A conductor Isis connected at one end to the shell ['5 and atits-otherendto the lamp 25 and holdsthe. lamp in positionprojecting through theaperture in the cover, and an electrical resistance element 29" ofextremely high resistance isconnected at one end to the other side ofthe lamp 25 by aconductor 30' and connected at its other end to thestrip It by a conductor 31.

The glow lamp 25 1s preferably agasflll'edlamp; a lamp filledwith neongas being preferred, having spaced apart-electrodes therein; one ofwhich is connected to the conductor 28 and the other to the conductor 30whereby the lamp is caused to glow when supplied with electrical energyat suflicient voltage.

A plug 32 of elongated, rectangular cross sectional shape has asemi-circularly rounded end 33. Its other end is recessed to provide agroove 34 extending between the narrower sides thereof and a partlycylindrical recess 35 extending inwardly of the inner side of the groove34 between the narrower sides of the plug. The plug is tapered in widthfrom its rounded end to its recessed end and the portion of the recessll of rectangular cross sectional shape is correspondingly tapered fromits open end toward the closed end of the body, so that the plug 32 willfit tightly into the corresponding portion of the recess.

The plug 32 is provided with shallow grooves extending one along each ofthe narrower sides thereof from the recessed end of the plug to alocation intermediate the length of the plug and terminating in inwardlyextending notches, and a strip 35' of fuse material has its end portionsoffset and inserted in the notches in the narrower sides of the plug.This strip extends along the shallow grooves in the narrower sides ofthe plug and across the recessed end of the plug within the recess 34and is of substantially U- shaped form, as is particularly illustratedin Figure 2. The bight portion of the fuse strip extending across thesecured end of the fuse plug 32 is notched intermediate its length in amanner well known to the art to provide in this strip a portion ofpredetermined electrical resistance which will burn out if the fuse issubjected to a current overload of a predetermined value.

The plug 32 is insertable through the aperture 23 in the cover 20 intothe rectangular portion of the recess ii and between the strips 58 and[9, so as to bring the portions of the fuse strip 36 extending along thenarrower sides of the plug into firm, electrically conductive contactwith the strips i8 and I9 as illustrated in Figure 3.

The cover 20 is provided at respectively opposite sides of the aperture23 in the cover and substantially midway the length of the longer sidesof this aperture with downwardly or inwardly extending apertured cars 38and 39 received in grooves provided in the adjacent end of body it and aU-shaped bail 49, formed of suitable wire, has laterally outwardlyoifset end portions pivotally received one in each of the ears 3B and39, so that the bail extends over the rounded end portion of the plug32. The plug 32 is provided at the mid-length location of thecylindrically rounded end surface thereof with a notch ll which receivesthe bight portion of the bail 60 when the plug is fully inserted intothe body H] to firmly secure the fuse plug in operative position in thebody with the fuse strip 35 in electrically conductive engagement withthe contact strip i8 and [9.

As long as the plug is properly positioned in the body l and the fusestrip 36 is intact, the electric current will flow through the fusestrip and the lamp 25 will not glow because the resistance unit 29 willforce so much of the current to flow through the fuse strip thatinsufficient voltage will be impressed on the lamp 25 to illuminate thelamp. However, if the fuse strip is ruptured, then the entire voltagewill be impressed on the lamp 25 causing the lamp to glow and indicatethat the fuse has blown. The lamp will also glow if the circuit iscompleted with the plug 32 removed, thereby enabling an electrician todetermine the fuse to which a articular circuit is connected in a wiringsystem.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is, therefore, to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are, therefore, intended to be embracedtherein.

What is claimed is:

1. In a fuse plug, an insulated body having a receptacle entering endand another end, said body being provided with a central recess openingthrough said other end of the body, said central recess being elongatedin the direction of the receptacle entering end of the body andtermimating in longitudinally spaced relation thereto, a center externalcontact on said entering end of the body having a portion extendingthrough said entering end into said recess, conductive strips extendinglongitudinally along opposite sides of said recess, one of said stripsbeing connected at one end to said portion of the center contact andhaving a free end, a conductive shell mounted around the exterior ofsaid body, the other of said conductive strips having an end connectedto said shell and another end unconnected with said center contact, saidrecess having a lateral extension at one side thereof and locatedbetween said conductive strips, said extension opening into said recess,a glow lamp supported in said extension, said glow lamp having one sidethereof connected to said shell and another side connected to said otherconductive strip, and a removable plug fitting said recess and disposedtherein, said plug having a fuse element including side portionsextending along opposite sides of said plug in engagement with saidconductive strips and a bight portion extending between and connected tosaid side portions, the side of said plug exposed in the recessextension serving as a wall bounding the open side of the recessextension.

2. In a fuse plug, an insulated body having a receptacle entering endand another end, said body being provided with a central recess openingthrough said other end of the body, said central recess being elongatedin the direction of the receptacle entering end of the body andterminating in longitudinally spaced relation thereto, a center externalcontact on said entering end of the body having a portion extendingthrough said entering end into said recess, conductive strips extendinglongitudinally along opposite sides of said recess, one of said stripsbeing connected at one end to said portion of the center contact andhaving a free end, a conductive shell mounted around the exterior ofsaid body, the other of said conductive strips having an end connectedto said shell and another end unconnected with said center contact, saidrecess having a lateral extension at one side thereof and locatedbetween said conductive strips, said extension opening into said recess,a glow lamp supported in said extension, said glow lamp having one sidethereof connected to said shell and another side connected to said otherconductive strip, and a removable plug fitting said recess and disposedtherein, said plug having a fuse element including side portionsextending along opposite sides of said plug in engagement with saidconductive strips and a bight portion extending between and connected tosaid side portions, the side of said plug exposed in the 5 recessextension serving as a wall bounding the open side of the recessextension, a cover on said other end of said body, said cover having anopening registering with the open end of said recess and having aportion closing the open end 1 of the recess extension, and meansmounting said References Cited in the file of this patent UNITED STATESPATENTS Number Name Date 0 2,266,841 Altschule Dec. 23, 1941 2,416,494Peterson Feb. 25, 1947

